In recent years, the electronic ballast using charging capacitor and high frequency AC source for power factor correction (PFC) has become a very attractive circuit topology. The charging capacitor adjusts the waveform of the input current in a way similar to a “charge pump”, so such kind of circuit is also called “charge pump” power factor regulator. FIG. 1 shows a typical charge pump electronic ballast circuit. The charge pump electronic ballast comprises a bridge rectifying circuit, a charge pump circuit composed of a pump capacitor Cin, a diode Dc and an energy storage capacitor CB, a DC/AC inverter circuit composed of transistors Q1 and Q2, a resonant circuit composed of an inductor Lr1 and a capacitor Cr1, and a DC blocking capacitor Cb1.
Said charge pump electronic ballast is usually designed with respect to the input voltage of 220V-240V, but when the input voltage is 220V-240V, there is a high voltage stress during the ignition of a lamp.
In some cases of application, however, the input voltage, i.e. the output voltage of the AC source is usually a low voltage such as 127V, so there is a need for a charge pump electronic ballast circuit for use with low input voltage, which could solve the problem of high voltage stress and is cost-effective and simple.